title: Proteolysis of human apolipoprotein B: effect on quantitative immunoturbidimetry.
abstract: Apolipoprotein (Apo) B100 is the obligatory structural protein of low and very low density lipoproteins. We studied the appearance of a kallikrein-induced proteolytic fragment of Apo B100, identified by sodium dodecyl sulphate (SDS)-polyacrylamide electrophoresis as Apo B74, in plasma samples obtained from 7 men and 7 women. We also studied the effect of Apo B74 on total Apo B immunoreactivity by immunoturbidimetry. Apo B74 was found in plasma from 4 of the 7 women when the samples had been stored at 4 degrees C in glass or plastic tubes, but in some of the samples from the men. These 4 women used oral estrogens. The plasma samples which contained Apo B74 showed evidence of kallikrein activation. Presence of Apo B74 resulted in an underestimation of total Apo B immunoreactivity by 13% (P less than 0.05).
authors.affiliation: Department of Medicine, University Hospital Utrecht, The Netherlands.
authors.forename: T W
authors.initials: TW
authors.lastname: De Bruin
authors.forename: M C
authors.initials: MC
authors.lastname: Vos
authors.forename: W
authors.initials: W
authors.lastname: Kortlandt
authors.forename: B N
authors.initials: BN
authors.lastname: Bouma
authors.forename: D W
authors.initials: DW
authors.lastname: Erkelens
mesh_terms: D000328:Adult; D001055:Apolipoproteins B / Q000097:blood*; D010450:Endopeptidases; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods; D011288:Prekallikrein / Q000378:metabolism
chemical_list: D001055:Apolipoproteins B; D011288:Prekallikrein; D010450:Endopeptidases